the resignation of one of our country's most decorated veterans. turns out now david petraeus was not the original focus of an fbi investigation. andrea mitchell first broke this story. she has more on how the fbi inadvertently found out about the general's affair. >> reporter: general david petraeus tumbled from the highest levels of government service after act thcknowledgint he called unacceptable behavior, an extramarital affair. another woman not related to petraeus felt she was being harassed and complained to the fbi. in recent weeks, the fbi traced the e-mails to broadwell and only stumbled upon the relationship with petraeus as a result. >> it's so politically sensitive that my guess is the decision was made near or at the top level of the fbi to sit down with general petraeus and have a discussion with him and let him know that this information had been discovered. >> reporter: broadwell has not been shy about her access to petraeus, co-hosting a barbecue with jon stewart. she spoke often about her connection to the cia director acknowledging it rubbed some in the military the wrong way.